U.S. Pat. No. 3,816,347, granted June 11, 1974 to Luh, discloses certain semiconductive elastomeric compositions based on chlorosulfonated polyethylene or chlorinated polyethylene elastomers, which semiconductive elastomeric compositions are useful to form vulcanized semiconductive outer layers on insulated electric cables. Such compositions are generally steam cured at temperatures of 130.degree.-205.degree. C. However, the high temperature thermal instability of such polymer compositions limits their use in new high-temperature curing processes. For example, the temperature of dry nitrogen gas curing commonly exceeds 300.degree. C. These high temperatures are designed to accelerate the rate of curing, but may approach the temperature at which significant degradation of the polymer composition will occur.
U.S. Pat. No. 3,904,588, granted Sept. 9, 1975 to Greene, discloses certain ethylene/alkyl acrylate/monoalkyl ester of 1,4-butenedioic acid copolymers, which copolymers are the basis for the semiconductive elastomeric compositions of the present invention. Greene does not disclose semiconductive compositions based on such copolymers, and perhaps most importantly, although Greene does disclose that the vulcanizates of such copolymers possess good heat aging resistance, Greene does not disclose suitability of such copolymers for high temperature curing.